Use Of The Ring Type Harness Method For Children
Daniel J. Gross, M.D.
In our experience, the fitting of above-elbow prostheses has presented a difficult problem. The difficulty involved in training above-elbow amputees to use their dual control systems is well known. Compounding this difficulty is the tendency of the prosthesis to shift and rotate on the shoulder resulting in instability and decreased prosthetic efficiency. Because of this, the patient tends to reject the above-elbow prosthesis. This is particularly true in amputees with short stumps or young children where the contour of the shoulder is not well adapted to conventional figure of eight harness methods. Many attempts have been made to provide stability by fabricating sockets with "modified" shoulder caps; and by modifying harness design and adding supplementary straps. One such harness method was described recently in The Orthopedic and Prosthetic Appliance Journal but to our way of thinking such modifications are both complicated and unnecessary.
In the past year we have been using the Northwestern Ring type harness,(1) which was developed originally for adult below-el-bow harnessing (Fig. 1 and Fig. 2 ). We have adopted this principle for all our harnessing and it is particularly beneficial in our short above-elbow prostheses. Since to date only adult sized rings are available commercially, we have made our own rings adapted to the size of the child and the width of the harness material to be used. Much to our surprise we have found not only greater acceptance of our prostheses because of the stability offered but also greater efficiency in the use of the prostheses from above ninety degrees elbow flexion to mouth height.
The harnessing is a basic figure of eight with ring instead of a fixed sewn point at the interscapular area. This allows the straps to adjust as the arm is brought to the mouth. In addition, a posterior elastic strap to the humeral cap is provided allowing uniform tension in all degrees of rotation. Although simple, this type harnessing has worked so well for us that we suggest its more universal use.
This very short above-elbow amputation was originally fitted at the age of five years. Because of prosthesis rotation a shoulder harness was attempted (Fig. 3 and Fig. 4 ). The patient accepted the prosthesis but did not perform any activities with the elbow above ninety degrees of flexion. A ring type harness was provided at age seven and the patient was able to achieve prosthetic function at the mouth with excellent stability of the prosthesis (Fig. 5 and Fig. 6 ). Note the posterior elastic strap to the humeral cap. In this fitting the ring is located higher on the back than is customary but we found this location provided maximum function without discomfort.
This three-year-old congenital hemimelia was first fitted with an above-elbow prosthesis at the age of three with a manual locking elbow device. We were unable to fabricate a socket of adequate stability for this child because of her "baby fat" and immature contours (Fig. 7 and Fig. 8 ). You will note the instability of the humeral socket on rotation and slippage of the socket on downward pressure. Following application of the prosthesis with a ring type harness and a positive elbow locking device, excellent stability and function resulted.
Daniel Gross is Clinic Chief Elizabethtown Child Amputee Clinic, Elizabethtown, Pennsylvania
Hampton, Fred, CP., and Sammons, Fred, O.T.R., "Ring Type Harness for Below Elbow Amputees," Northwestern University, Prosthetic Research Centre, Chicago, Illinois, 1961.